Timing belt should be replaced since it has passed 105,000 miles according to Subaru scheduled maintenance guide.

Rear differential mounts are damaged. Replace.

Rack and pinion are leaking. Replace.

Money is tight for me and as for most of us. What is/are the essential repairs or replacement I should be doing for it?

I don't drive recklessly or drive in severe conditions. Maximum mileage per month would be about 200 miles, mostly highway. Sometimes in stop and go traffic.

I was thinking the timing belt and CV axle half shaft as top priority to replace.

Below are more details.

CV boots - it's torn through and leaking grease. Because the car has been driven while it's leaking, grease could be seen on the surfaces of other components surrounding the half shaft axle. There's also dirt built-up wherever there's grease, since the grease in the CV boots are thick and sticky. The clamps are still securely in place.

Shall I replace the CV boots ONLY instead of replace the entire driver side half shaft axle?The axle is Subaru stock. I am thinking it's of better quality since the axle from autozone (retail parts/accessories store) is re-manufactured.

Transmission mounts - it appears the screws on the mount that are supposed to be attached to the transmission are broken. When a crowbar is used, the whole transmission could lifted off the transmission mounts. One indication I notice is whenever I put the car into reverse from neutral, the car jerks/clunks with a loud thud that could be heard from the inside. If I waited longer to feel the reverse gear in place for about 2 seconds, it will reverse smoothly. No noticeable lunges or knocks while accelerating or decelerating.

Rear differential mounts - it hard to view this component as this is my first time looking at it. It appears the rear differential mounts (2 bolts) are not securely attached to the rear differential. No differential fluid leakage whatsoever though.

Steering gear (rack and pinion) - Wet verses. The steering is still generally smooth but it may shudder when negotiating 90 degree sharp turns. There's no power steering leakage. The power steering belt is in excellent condition.

I actually have photos of all the above but I am not sure whether I can post pictures on repairpal.